Developments in technology have been accompanied by an increased reliance on fuel sources. Such fuel sources are becoming increasingly limited and difficult to acquire. With the burning of fossil fuels taking place at an unprecedented rate, it is likely that the world's fuel demand will soon outweigh current fuel supplies.
As a result, efforts have been directed toward harnessing sources of renewable energy, such as sunlight, water, wind, and biomass. The use of biomasses to produce new sources of fuel which are not derived from petroleum sources, (i.e., biofuel) has emerged as one alternative option. Biofuel is a biodegradable, clean-burning combustible fuel which can be comprised of alkanes and esters. An exemplary biofuel is biodiesel. Biodiesel can be used in most internal combustion diesel engines in either a pure form, which is referred to as “neat” biodiesel, or as a mixture in any concentration with regular petroleum diesel.
Biodiesel offers a number of interesting and attractive beneficial properties compared to petroleum-based diesel, including reduced emissions (e.g., carbon monoxide, sulphur, aromatic hydrocarbons, soot particles, etc.) during combustion. Biodiesel also maintains a balanced carbon dioxide cycle because it is based on renewable biological materials. Biodiesel is non-toxic, completely biodegradable, and very safe due to its high flash point and low flammability. Furthermore, biodiesel provides good lubrication properties, thereby reducing wear and tear on engines.
Current methods of making biodiesel involve transesterification of triacylglycerides from vegetable oil feedstocks, such as rapeseed in Europe, soybean in North America, and palm oil in South East Asia. Industrial-scale biodiesel production is thus geographically and seasonally restricted to areas where vegetable oil feedstocks are produced. The transesterification process leads to a mixture of fatty esters which can be used as biodiesel. An undesirable byproduct of the transesterification process is glycerin. To be usable as biodiesel, the fatty esters must be further purified from the heterogeneous product. This increases costs and the amount of energy required for fatty ester production and, ultimately, biodiesel production as well. Furthermore, vegetable oil feedstocks are inefficient sources of energy because they require extensive acreage for cultivation. For example, the yield of biodiesel from rapeseed is only 1300 L/hectare because only the seed oil is used for biodiesel production, and not the rest of the rapeseed biomass. Additionally, cultivating some vegetable oil feedsocks, such as rapeseed and soybean, requires frequent crop rotation to prevent nutrient depletion of the land.
Therefore, there is a need for an economically- and energy-efficient biofuel and method of making biofuels from renewable energy sources, such as biomass.